When water is being supplied to a home or building from a supply line connected to a pump or central water source, it is desirable to provide a back flow valve which will preclude flow of contaminated liquid back into the water system.
The present invention is directed to a back flow valve which is effective, low in cost, has long life, and will not be adversely affected by long periods of non-use or by foreign matter.
The back flow valve embodying the invention comprises a housing having an inlet and an outlet and a tube mounted in the housing and having an open end communicating with the inlet to the housing. The tube has the other end thereof closed, and has a plurality of circumferentially and longitudinally spaced openings at the center thereof such that liquid can only flow from the inlet to the housing through the openings to the outlet of the housing. An elastic sleeve is telescoped over the tube and normally closes the openings, the inside diameter of the sleeve being less than the outer diameter of the tube. The tube has longitudinally spaced abutments adjacent the ends of the sleeve and the length of the sleeve is less than the longitudinal distance between the abutments. The ends of the sleeve have portions thereof extending axially beyond other portions thereof such that as liquid pressure is built up, the liquid stretches the sleeve and flows out of the openings in the tube and along the exterior of the tube and the liquid engages the abutments and in cooperation with the longitudinally extending portions causes said sleeve to rotate facilitating the opening and closing of the sleeve even after prolonged periods of time.
Although various prior art uses have been made of elastic sleeves in valves for various purposes, such as in U.S. Pat. Nos. 384,306, 1,800,066, 2,662,485, 3,179,124 and 3,448,766, I am not aware that such patents have been successful in actual use for controlling the flow of liquid to or from a home or building. Moreover, the constructions of back flow valve known in these patents differ in structure and function from that of my invention.